Method for operating a water-carrying household appliance

ABSTRACT

A method for operating a water-conducting domestic appliance is provided. During at least one of a plurality of successive partial program steps, a first medium is heated at least at times by means of a first heating element and items undergoing treatment are heated by applying the heated first medium to the items. When the first heating element is inactive, a second medium is heated at least at times by means of a second heating element and the items undergoing the treatment are heated &#39;by the heated second medium.

The invention relates to a method for operating a water-conductingdomestic appliance, in particular a dishwasher or tumble dryer accordingto the preamble of claim 1.

Known from DE 10 2005 004 089 A1 is a method for operating awater-conducting domestic appliance, which is to say a dishwasher. Asorption device having a reversibly dehydratable material is provided asthe drying system which during a drying step removes and stores a volumeof water from the air requiring to be dried. Taking place at an ensuingcleaning step is a regeneration process or, as the case may be,desorption during which an air current flowing through the drying meansis heated by means of an air heater. The volume of water stored in thedrying means is released as hot water vapor with the heated air currentand returned to the washing container and the items requiring to bewashed are heated. That kind of heating is, though, time-consuming.

The object of the invention is hence to provide a method for operating awater-conducting domestic appliance, which method allows the timerequired to be reduced.

The invention proceeds from a method for operating a water-conductingdomestic appliance, in particular a dishwasher or tumble dryer, whichmethod includes a plurality of successive partial program steps duringat least one of which a first medium is heated at least at times bymeans of a first heating element and items undergoing treatment areheated by being subjected to the heated first medium.

It is inventively provided for a second medium to be heated at least attimes by means of a second heating element when the first heatingelement is inactive and for the items undergoing treatment to be heatedby means of the heated second medium. A greater performance capabilityof the second heating element therein allows the heating process to beaccelerated. It is furthermore ensured thereby that the powerconsumption will remain below a maximum power consumption of thewater-conducting domestic appliance. The maximum power consumption islimited by the maximum power capacity of the domestic power supplyserving to supply the water-conducting domestic appliance with electricenergy. A level of power consumption by the water-conducting domesticappliance that exceeds the domestic power supply's maximum powercapacity will cause the domestic power supply to be overloaded with theresult that protective elements such as, for example, fusible cutouts orautomatic circuit breakers will be triggered and a further supply ofenergy prevented. Uninterrupted operation of the water-conductingdomestic appliance will thus be ensured.

It is further preferably provided for the first medium to be a gaseousmedium and the second medium a liquid medium. The liquid medium'sgreater heat capacity therein reduces the length of heating time. Thegaseous medium can be heated by means of an electric air heater, forexample supported by a ventilating fan for circulating the gaseousmedium. The liquid medium can be heated by means of a continuous-flowheater, for example supported by a circulating pump for circulating theliquid medium.

In a first, preferred embodiment variant it is provided for a firstmedium to be heated during the partial program step at least at times bymeans only of the first heating element and for a second medium to beheated at least at times by means only of the second heating element.

In a further, preferred embodiment variant it is provided for a firstmedium to be heated during a first partial program step at least attimes by means only of the first heating element and for a second mediumto be heated during a second partial program step at least at times bymeans only of the second heating element.

The two heating elements are therefore operated only in an alternatingmanner either during a single partial program step or during at leasttwo partial program steps. It will be ensured thereby that overheatingcannot occur inside the water-conducting domestic appliance on accountof at least at times simultaneous operation of the two heating elementsresulting in, for example, damage to one of the two heating elementsand/or to a sorption device having a reversibly dehydratable material,for example zeolite.

Preferably it is provided for items undergoing treatment to be subjectedduring an ensuing partial program step to a second medium. Said step cantherein be a pre-washing step during which in the case of, for example,a dishwasher coarse soiling of the items undergoing treatment or, as thecase may be, being washed is removed, or it can be a cleaning stepduring which a cleansing agent is added for removing stubborn dirt.

It is further preferably provided for a medium, for example washingwater, to be replaced at least once between two partial program steps. Amixed temperature develops that is between the temperature of the liquidmedium and that of the items undergoing treatment after the firstpartial program step. The difference in temperature to be overcomebetween the mixed temperature and the maximum temperature requiring tobe attained during the cleaning step will be correspondingly less sothat correspondingly less energy will have to be expended.

It is furthermore preferably provided for a cleansing agent to be addedduring a partial program step embodied as a cleaning step for cleaningitems undergoing treatment.

It is also preferably provided for a partial program step embodied as apre-washing step for cleaning items undergoing treatment without theaddition of a cleansing agent to be performed before the cleaning stepso that the pre-washing step will be performed directly before thecleaning step at which higher temperatures are attained than during thepre-washing step.

It is therein preferably provided for a post-washing phase to take placeduring the cleaning step, during which phase items undergoing treatmentare warmed by being subjected to a second medium heated by means of thesecond heating element.

In a further embodiment variant it is preferably provided for a partialprogram step to be embodied as a final rinsing step with heating ofwashing water during which surfactants are added.

It is further provided for a partial program step embodied as anintermediate rinsing step for cleaning items undergoing treatmentwithout the addition of a cleansing agent to be performed before thefinal rinsing step so that the intermediate rinsing step will beperformed directly before the final rinsing step at which highertemperatures are attained than during the intermediate rinsing step.

It is furthermore preferably provided for a drying step to be performedas the final partial program step during which the second medium isabsorbed by a reversibly dehydratable material. Liquid stored again inthe reversibly dehydratable material will hence be available for arenewed treatment cycle.

It is therein preferably provided for the reversibly dehydratablematerial to be at least partially desorbed during a partial program stepso that the reversibly dehydratable material will then be absorbentagain.

Two exemplary embodiments of the invention are described below with theaid of the attached figures.

FIG. 1 is a schematic block diagram of a dishwasher for executing awashing method according to the first exemplary embodiment,

FIG. 2 is a temperature-time chart for illustrating a washing-programsequence in a first energy-saving washing operating mode,

FIG. 3 is a time chart representing only the cleaning step forillustrating a washing method in the second, time-saving washingoperating mode according to the first exemplary embodiment, and

FIG. 4 is a chart corresponding to FIG. 3 according to the secondexemplary embodiment.

Shown in FIG. 1 as an exemplary embodiment of a water-conductingdomestic appliance is a dishwasher having a washing container 1 in whichitems requiring to be washed (not shown) can be arranged in crockerybaskets 3, 5. Arranged in washing container 1 shown here as examples ofspraying devices are two spray arms 7, 9 that are provided in differentspraying planes and via which the items requiring to be washed aresubjected to washing liquid. Provided in the washing-container base is apump body 11 having a circulating pump 13 that is fluidically connectedvia feed pipes 14, 15 to spray arms 7, 9. Pump body 11 is joined alsovia connecting branches to a fresh-water feed pipe 16 coupled to thewater-supply network as well as to a drainage pipe 17 in which a drainpump 18 for pumping the washing liquid out of the washing container islocated.

Washing container 1 has in its upper region an outlet opening 19connected via a pipe 21 to a drying device embodied as a sorption device22. An air blower 27 and a heating element 24 are connected in pipe 21to sorption device 22. Sorption device 22 contains as the drying means areversibly dehydratable material such as, for instance, zeolite by meansof which air is dried at a drying step T. A heavily moisture-laden aircurrent is for that purpose ducted by means of air blower 27 fromwashing container 1 through sorption device 22. The zeolite provided insorption device 22 absorbs the moisture in the air and the relativelydry air is returned to washing container 1.

Volume of water m₂ stored in the zeolite at drying step T can bereleased again during a regeneration process, which is to say during adesorption process, by heating the drying means of sorption device 22.An air current heated to very high temperatures by heating element 24 isfor that purpose ducted through sorption device 22 by means of fan 27,released as hot water vapor with the water stored in the zeolite, andthus returned to washing container 1.

FIG. 2 shows a time-based program sequence having the individual partialprogram steps comprising a washing operation namely pre-washing V,cleaning R, intermediate rinsing Z, final rinsing K, and drying T.

The above-described regeneration process in sorption device 22 takesplace in the temperature-time profile shown in FIG. 2 during timeinterval Δt_(R). The partial program steps indicated in FIG. 2 arecontrolled by means of a control device 25 by appropriately drivingcirculating pump 13, drain pump 18, air blower 23, drying device 22, andother control components.

Regeneration process At_(R) starts according to FIGS. 2 and 3 at thebeginning of cleaning step R at instant t₀. Volume of water m₂ stored inthe drying means is returned as water vapor to washing container 1during regeneration process Δt_(R). Said volume of water m₂ was removedfrom the moisture-laden air current requiring to be dried at drying stepT of the preceding washing operation during an adsorption processΔt_(A). The volume of washing liquid m_(iss) made available overall atcleaning step R is hence the totality of a volume of fresh water m addedvia fresh-water pipe 16 and volume of water m₂ returned duringregeneration process Δt_(R).

During heating phase Δt_(H) taking place at the beginning of cleaningstep R, heating initially takes place during regeneration process Δt_(R)by means of second heating element 24, which is to say the air heater bymeans of which a heating capacity Q₂ is introduced into washingcontainer 1. A heating capacity Q₁ is then introduced into washingcontainer 1 by means of first heating element 23, which is to say thewater heater. Heating capacity Q₁ of water heater 23 can be around 2200W while heating capacity Q₂ of air heater 24 is of an order of magnitudeof only 1400 W.

As proceeds from FIG. 2, during heating phase Δt_(H) the washing liquidis heated initially by means only of the water vapor that is releasedduring regeneration process Δt_(R) and can heat the washing liquid bymeans of heating capacity Q₂ to a temperature T₁ of approximately 40° C.by way of example here. Water heater 23 operating at a far greaterheating capacity Q₁ is not cut in until after regeneration processΔt_(R) has ended. Thermal damage to the drying means in the sorptiondevice can be avoided by water heater 23 that is not cut in until afterregeneration process Δt_(R) has ended. By means of water heater 23 thatis cut in it is possible to raise the temperature of the washing liquidfurther from temperature T₁ of 40° C. to cleaning temperature T_(R) thatcan be 51° C. by way of example here.

In the first operating mode, shown in FIG. 2, the heat Q₂ releasedduring regeneration process Δt_(R) is therefore used in an energy-savingmanner for heating washing liquid m_(ist) during heating phase Δt_(H).

As further proceeds from FIG. 1, control device 25 has a signal link toa changeover switch 26 that can be manually operated by a user.Operating changeover switch 26 will enable a user to change over fromthe first energy-saving washing operating mode described above with theaid of FIG. 2 to a second washing operating mode described below.

In the second washing operating mode the volume of washing liquid isheated at cleaning step R during what compared with the first washingoperating mode is a temporally reduced heating phase Δt_(H), as is shownin FIG. 3. FIG. 3 shows heating phase Δt_(H) of both the first washingoperating mode (dashed line) and the second washing operating mode(unbroken line). As proceeds from FIG. 3, regeneration process Δt_(R) isbrought forward in time in the second washing operating mode. That is tosay regeneration process Δt_(R) here already starts during pre-washingstep V and temporally overlaps start time t₀ of cleaning step R.Bringing regeneration process Δt_(R) forward in time enables waterheater 23 that operates at a far greater heating capacity Q₁ to beginheating the washing liquid in the washing container sooner with nodanger of thermal damage being sustained as a result by the zeoliteprovided in sorption device 22.

Cleaning temperature T_(R) will in that way be attained in anaccelerated manner in the second washing operating mode, as a result ofwhich cleaning step R₁ can analogously also be ended at an earlierinstant t_(E1). Water heater 23 can—as an alternative to the exemplaryembodiment shown—even be started at start time t₀ of cleaning step R₁ ifthe regeneration process is suitably positioned in time terms relativeto start time t₀ of cleaning step R. That is because at the start of theheating phase water heater 23 initially only heats the washing liquid inwashing container 1 and the air only after a time delay. Thus at thestart of heating phase Δt_(H1) there is no risk of an over-heated aircurrent reaching sorption device 22 during regeneration process Δt_(R)and thermally damaging the zeolite.

Described in FIG. 4 is a washing method taking place during the secondwashing operating mode according to the second exemplary embodiment.Regeneration process Δt_(R) takes place in contrast to FIG. 3 totallyoutside heating phase Δt_(H). Regeneration process Δt_(R) is furthermoredivided into temporally mutually separate regeneration segments Δt_(R1),Δt_(R2) which by way of example are approximately equally long in FIG.4. As proceeds from FIG. 4, first regeneration segment Δt_(R1) takesplace already at pre-washing step V. Second regeneration segment Δt_(R2)then starts after heating phase Δt_(H) during post-washing time N.

LIST OF REFERENCES

-   1 Washing container-   3 Crockery basket-   5 Crockery basket-   7 Spray arm-   9 Spray arm-   11 Pump body-   13 Circulating pump-   14 Feed pipe-   15 Feed pipe-   16 Fresh-water feed pipe-   17 Drainage pipe-   18 Drain pump-   19 Outlet opening-   21 Pipe-   22 Drying device-   23 Heating element-   24 Heating element-   25 Control device-   26 Changeover switch-   27 Air blower-   29 Temperature sensor-   V Pre-washing-   R Cleaning-   Z Intermediate rinsing-   K Final rinsing-   T Drying-   T_(R) Cleaning temperature-   Δt_(A) Adsorption process-   Δt_(H) Heating phase-   Δt_(R) Regeneration process-   m₁ Volume of fresh water added-   m₂ Volume of water returned-   m_(ist) Volume of washing liquid-   Q₁ Heating capacity-   Q₂ Heating capacity-   t₀ Start time of cleaning step R-   t_(E) End time of cleaning step R

1-13. (canceled)
 14. A method for operating a water-conducting domesticappliance, the method comprising: during at least one of a plurality ofsuccessive partial program steps heating a first medium at least attimes by means of a first heating element and heating items undergoingtreatment by applying the heated first medium to the items; and when thefirst heating element is inactive, heating a second medium at least attimes by means of a second heating element and heating the itemsundergoing the treatment by the heated second medium.
 15. The method ofclaim 14, wherein the water-conducting domestic appliance is one of adishwasher and a tumble dryer.
 16. The method of claim 14, wherein thefirst medium is a gaseous medium and the second medium is a liquidmedium.
 17. The method of claim 14, wherein the first medium is heatedduring the partial program step at least at times by means of the firstheating element only and the second medium only is heated at least attimes by means of the second heating element.
 18. The method of claim14, wherein the first medium is heated during a first partial programstep at least at times by means only of the first heating element andthe second medium is heated during a second partial program step atleast at times by means only of the second heating element.
 19. Themethod of claim 14, wherein, in the partial program step, the secondmedium is subsequently applied to the items undergoing the treatment.20. The method of claim 14, wherein at least one of the first medium andthe second medium is replaced at least once between two partial programsteps.
 21. The method of claim 20, wherein the second medium is replacedat least once between the two partial program steps.
 22. The method ofclaim 14, wherein a cleansing agent is added during a cleaning step inorder to clean the items undergoing the treatment.
 23. The method ofclaim 22, wherein, before the cleaning step, a pre-washing step forcleaning the items undergoing the treatment is performed without theaddition of the cleansing agent.
 24. The method of claim 22, wherein,during the cleaning step, a post-washing phase takes place during whichthe items undergoing the treatment are warmed by applying the secondmedium that is heated by means of the second heating element to theitems.
 25. The method of claim 14, wherein, during a final rinsing step,washing water is heated and surfactants are added.
 26. The method ofclaim 25, wherein, before the final rinsing step, an intermediaterinsing step for cleaning the items undergoing the treatment isperformed without adding a cleansing agent.
 27. The method of claim 14,wherein a drying step is performed as a final partial program stepduring which the second medium is absorbed by a reversibly dehydratablematerial.
 28. The method of claim 27, wherein the reversiblydehydratable material is at least partially desorbed during a partialprogram step.